The present invention relates to an infrared-sensitizing dye and infrared-sensitive photographic materials by the use thereof and in particular to a photographic material and a thermally developable photothermographic material by the use of an infrared-sensitive silver halide emulsion exhibiting a high sensitivity, a low fog and reduced variation in sensitivity following storage.
There are known silver halide photographic light sensitive materials employing silver halide grains and photo-recording materials employing photopolymerization or cleavage reaction. However, the longest photosensitivity edge of the silver halide grains is in the vicinity of 500 nm and the photosensitivity region of photopolymers is in a ultraviolet region so that spectral sensitization by use of dyes is indispensable to provide sensitivity at the loner wavelength side. Particularly with recent progress in light sources, importance of photosensitive materials sensitive to the laser wavelength region increases in the field of recording materials for industrial use. Further in the field of picture-taking photosensitive materials are noted infrared photosensitive materials used for recording environment information and superior in portrayability.
There are known a number of compounds as a sensitizing dye or spectral sensitizing dye, including cyanine dyes and merocyanine dyes described in T. H. James xe2x80x9cThe Theory of the Photographic Processxe2x80x9d Fourth ed. (1977, Macmillan Co. N.Y.) pages 194-234; F. M. Hammer xe2x80x9cThe Cyanine Dyes and Related Compoundsxe2x80x9d (1964, John Wiley and Sons, N.Y.); D. M. Sturmer xe2x80x9cThe Chemistry of Heterocyclic Compoundsxe2x80x9d vol. 30, page 441 (1977, John Wiley and Sons, N.Y.); JP-A 3-138638, 3-163440, 5-72660, 5-72661, 5-88292, 8-194282, 9-166844, 9-281631, 9-282672, 9-292673 and 10-73900 (hereinafter, the term, JP-A means a unexamined and published Japanese Patent Application); U.S. Pat. Nos. 2,320,439, 2,398,999, 2,734,900, 3,582,344, 4,536,473, 4,740,455, 4,835,096, and 5,393,654; British Patent 774,779, 625,245, and 895,930; European Patent 420,012 and 821,811.
These sensitizing dyes and spectral sensitizing dyes are required not only to expand spectral sensitivity region but also to satisfy the following conditions:
1) optimum spectral sensitization region,
2) high spectral sensitization efficiency (sensitivity),
3) no unfavorable interaction with other additives such as a stabilizer, antifoggant, coating aid, high boiling solvent and binder,
4) no adverse effect on the characteristic curve such as fogging or contrast variation,
5) no variation in photographic performance such as reduction in a S/N ratio or sensitivity when the dye containing photosensitive material is aged (particularly when aged at a high temperature or high humidity),
6) no diffusion of an added sensitizing dye to a different photosensitivity layer, causing color mixing, and
7) removal or discoloration of the dye after development, fixing and washing, causing no color stain.
However, commonly known spectrally sensitizing dyes have not satisfied these conditions to sufficiently satisfactory levels. Specifically, photosensitive materials to be recorded by using a laser light source are desired to have a high absorption fitted to the bright line wavelengths. However, a dye having an absorption in the region of red to infrared contains a long conjugated chain and is so susceptible to environments that although exhibiting a high molar extinction coefficient in a solution, phenomena easily occur such that the dye discolors during the preparation process or causes a number of conformational changes, forming a broad absorption spectrum exhibiting a low absorption maximum. Further, the energy gap between the lowest unoccupied level and the highest occupied level is so narrow that the lowest unoccupied level and the highest occupied level are close to the conduction band level of silver halide grains, producing problems that fogging easily occur or sensitivity is reduced.
Accordingly, there are desired an infrared-sensitive recording material exhibiting high sensitivity in the region of red to infrared and further an infrared sensitive recording material exhibiting high sensitivity and low fog and reduced variation in performance even when being aged.
Infrared sensitizing dyes generally exhibit a lower adsorption to silver halide grains than dyes sensitizing to the visible region, producing problems such as low sensitivity or marked desensitization during pre-exposure storage during standing in the form of a solution in the process of preparing a coating solution. There have been made various attempts of overcoming these problems by varying the structure of the dye. However, disclosed dyes have not yet reached levels solving the problems.
Accordingly, an object of the present invention is to provide an image forming composition exhibiting a high sensitivity to infrared laser light exposure and an image forming method by the use thereof, and in particular an infrared sensitive silver halide emulsion exhibiting a high sensitivity and low fog and superior in storage stability, a silver halide photographic light sensitive material and thermally developable photosensitive material containing the emulsion and an image forming method by the use of the materials.
An object of the invention is to provide a thermally developable photosensitive material exhibiting a high sensitivity and reduced desensitization during pre-exposure storage and preparation method thereof.
An object of the invention is to provide a thermally developable photosensitive material exhibiting little variation in photographic performance even when a standing time of a photosensitive solution is extended during the preparation thereof, in particular, a preparation method of the photosensitive solution and a coating method thereof.
An object of the invention is to provide an image recording method and image forming method by use of a thermally developable photosensitive material accomplishing the objects described above.
The above objects of the invention can be accomplished by the following constitution:
1. A spectral sensitizing dye represented by the following formulas (1) to (4): 
wherein Y1, Y2 and Y11 each are independently an oxygen atom, a sulfur atom, a selenium atom, xe2x80x94C(Ra)(Rb)xe2x80x94 group or xe2x80x94CHxe2x95x90CHxe2x80x94 group, in which Ra and Rb each are a hydrogen atom, a lower alkyl group or an atomic group necessary to form an aliphatic spiro ring between Ra and Rb; Z1 is an atomic group necessary to form a 5- or 6-membered ring; R is a hydrogen atom, a lower alkyl, a cycloalkyl group, an aralkyl group, a lower alkoxy group, an aryl group, a hydroxy group or a halogen atom; W1, W2, W3, W4, W11, W12, W13 and W14 each are independently a hydrogen atom, a substituent or a non-metallic atom group necessary to form a condensed ring by bonding between W1 and W2 or W11 and W12; R1 and R11 are each an aliphatic group or a non-metallic atom group necessary to form a condensed ring by bonding between R1 and W3 or R11 and W14; V1 to V9, and V11 to V13 each are independently a hydrogen atom, a halogen atom, an amino group, an alkylthio group, an arylthio group, a lower alkyl group, a lower alkoxy group, an aryl group, an aryloxy group, a heterocyclic group or a non-metallic atom group necessary to form a 5- to 7-membered ring by bonding between V1 and V3, V2 and V4, V3 and V5, V2 and V6, V5 and V7, V6 and V8, V7 and V9, or V11 and V13, provided that at least one of V1 to V9 and at least one of V11 to V13 are a group other than a hydrogen atom; X1 and X11 each are an ion necessary to compensate for an intramolecular charge; 11 and 111 each an ion necessary to compensate for an intramolecular charge; k1 and k2 each are 0 or 1; p1 and p11 are each 0 or 1; q1 and q11 each are 1 or 2, provided that the sum of p1 and q1 and the sum of p11 and q11 are respectively not more than 2; 
wherein Y21, Y22 and Y31 each are independently an oxygen atom, a sulfur atom, a selenium atom, xe2x80x94C(Ra)(Rb)xe2x80x94 group or xe2x80x94CHxe2x95x90CHxe2x80x94 group, in which Ra and Rb each are a hydrogen atom, a lower alkyl group or an atomic group necessary to form an aliphatic spiro ring between Ra and Rb; R21, R22, R31 and R32 each are independently an aliphatic group; Rc and Rd each are independently an unsubstituted lower alkyl group, a cycloalkyl group, an aralkyl group, an aryl group or a heterocyclic group; W21, W22, W23, W24, W31, W32, W33 and W34 each are independently a hydrogen atom, a substituent or a non-metallic atom group necessary to form a condensed ring by bonding between W21 and W22, W23 and W24, W31 and W32, or W33 and W34; V21 to V29, and V31 to V33 each are independently a hydrogen atom, a halogen atom, an amino group, an alkylthio group, an arylthio group, a lower alkyl group, a lower alkoxy group, an aryl group, an aryloxy group, a heterocyclic group or a non-metallic atom group necessary to form a 5- to 7-membered ring by bonding between V21 and V23, V22 and V24, V23 and V25, V24 and V26, V25 and V27, V26 and V28, V27 and V29, or V31 and V33; X21 and X31 each are an ion necessary to compensate for an intramolecular charge; 121 and 131 each an ion necessary to compensate for an intramolecular charge; k21 and k22 each are 0 or 1; n21, n22, n31 and n32 each are 0, 1 or 2, provided that n21 and n22, or n31 and n32 are not 0 at the same time;
2. The spectral sensitizing dye described 1 above, wherein the dye is represented by formula (1) or (2);
3. The spectral sensitizing dye described in 2 above, wherein the dye is represented by the following formula (1-1) or (2-1): 
wherein Y1, Y2 and Y11 each are independently an oxygen atom, a sulfur atom, a selenium atom, xe2x80x94C(Ra)(Rb)xe2x80x94 group or xe2x80x94CHxe2x95x90CHxe2x80x94 group, in which Ra and Rb each are a hydrogen atom, a lower alkyl group or an atomic group necessary to form an aliphatic spiro ring when Ra and Rb are linked with each other; Z1 is an atomic group necessary to form a 5- or 6-membered ring; R is a hydrogen atom, a lower alkyl, a cycloalkyl group, an aralkyl group, a lower alkoxy group, an aryl group, a hydroxy group or a halogen atom; W1, W2, W3, W4, W11, W12, W13 and W14 each are independently a hydrogen atom, a substituent or a non-metallic atom group necessary to form a condensed ring by bonding between W1 and W2 or W11 and W12; R1 and R11 are each an aliphatic group or a non-metallic atom group necessary to form a condensed ring by bonding between R1 and W3 or R11 and W14; L1 to L9, and L11 to L15 each are independently a methine group; X1 and X11 each are an ion necessary to compensate for an intramolecular charge; 11 and 111 each an ion necessary to compensate for an intramolecular charge; m1 to m3 each are 0 or 1; p1 and p11 are each 0 or 1; q1 and q11 each are 1 or 2, provided that the sum of p1 and q1 and the sum of p11 and q11 are respectively not more than 2;
4. The spectral sensitizing dye described in 1 above, wherein the dye is represented by formula (3) or (4);
5. The spectral sensitizing dye described 4 above, wherein the dye is represented by formula (3);
6. A silver halide photographic material comprising a support having thereon at least a photosensitive layer containing a silver halide emulsion layer, wherein said photosensitive layer contains a compound represented by the formulas (1) to (4) described above;
7. The photographic material described in 6 above, wherein the compound is represented by formula (1) or (2);
8. The photographic material described in 7 above, wherein the compound is represented by the formula (1-1) or (2-1) described above;
9. The photographic material described in 6 above wherein the compound is represented by the formula (3) or (4) described above;
10. The photographic material described in 9 above, wherein the compound is represented by the formula (3) described above;
11. The photographic material described in 10 above, wherein the photosensitive layer further contains a compound represented by the following formula (5): 
wherein Y4 and Y42 each are independently an oxygen atom, a sulfur atom, a selenium atom, xe2x80x94C(Ra)(Rb)xe2x80x94 group or xe2x80x94CHxe2x95x90CHxe2x80x94 group, in which Ra and Rb each are a hydrogen atom, a lower alkyl group or an atomic group necessary to form an aliphatic spiro ring together with Ra and Rb; R41 and R42 each are independently an aliphatic group; Re and Rf each are independently an unsubstituted lower alkyl group, cycloalkyl group, aralkyl group, aryl group or heterocyclic group; W41, W42, W43, and W44 each are independently a hydrogen atom, a substituent or a non-metallic atom group necessary to form a condensed ring by bonding between W41 and W42, W43 and W44; L41 to L49 are each a methine group; X41 is an ion necessary to compensate for an intramolecular charge; 141 is an ion necessary to compensate for an intramolecular charge; m42 and m43 each are 0 or 1; n41 and n42 each are 0, 1 or 2, provided that n41 and n42 are not 0 at the same time;
12. The photographic material described in 9 above, wherein said compound is represented by the formula (4) described above;
13. The photographic material described in 12 above, wherein the photosensitive layer further contains a compound represented by formula (6): 
wherein Y51 is independently an oxygen atom, a sulfur atom, a selenium atom, xe2x80x94C(Ra)(Rb)xe2x80x94 group or xe2x80x94CHxe2x95x90CHxe2x80x94 group, in which Ra and Rb each are a hydrogen atom, a lower alkyl group or an atomic group necessary to form an aliphatic Spiro ring together with Ra and Rb; R51 and R52 each are independently an aliphatic group; Re and Rf each are independently an unsubstituted lower alkyl group, cycloalkyl group, aralkyl group, aryl group or heterocyclic group; W51, W52, W53 and W54 each are independently a hydrogen atom, a substituent or a non-metallic atom group necessary to form a condensed ring by bonding between W51 and W52, or W53 and W54; L51 to L55 are each a methine group; X51 is an ion necessary to compensate for an intramolecular charge; 151 is an ion necessary to compensate for an intramolecular charge; n51 and n52 each are 0, 1 or 2, provided that n51 and n52 are not 0 at the same time;
14. The photographic material described in 6 above, wherein the photosensitive layer further contains an organic silver salt and a reducing agent;
15. The photographic material described in 14 above, wherein the compound is represented by the formula (1) or (2) described above;
16. The photographic material described in 15 above, wherein the compound is represented by the formula (1-1) or (2-1) described above;
17. The photographic material described in 14 above, wherein the compound is represented by the formula (3) or (4) described above;
18. The photographic material described in 17, wherein the compound is represented by the formula (3) described above;
19. The photographic material described in 18 above, wherein the photosensitive layer further contains a compound represented by the formula (5) described above;
20. The photographic material described in 17 above, wherein the compound is represented by the formula (4) described above;
21. The photographic material described in 20 above, wherein the photosensitive layer further contains a compound represented by the formula (6)described above;
22. The photographic material described in 14 above, wherein the photographic material further has a non-photosensitive layer, said non-photosensitive layer containing a binder, a phthalazine compound, a benzenepolycarboxylic acid or an acid anhydride compound;
23. An image forming method comprising exposing a photosensitive material to laser, the photosensitive material comprising a support having thereon at least a photosensitive layer containing a compound represented by the formulas (1) to (4) described above;
24. The image forming method described in 23 above, wherein the compound is represented by the formula (1) or (2) described above;
25. The image forming method described in 24 above, wherein said compound is represented by the formula (1-1) or (2-1 described above.
The invention will be further described. It was found according to the inventors of the invention that the invention was accomplished by the use of the compounds represented by formulas (1) to (6) as an infrared sensitizing dye or an infrared sensitizer dye.
One feature of the infrared sensitizing dye according to the invention concerns a three ring-condensed heterocyclic nucleus formed by bonding between a nitrogen atom contained in a benzothiazole ring and a carbon atom at the peri-position; and another feature is a long chain polymethine dye, in which a sulfonyl group is substituted on the benzene ring of the benzothiazole ring, leading to high sensitivity, low fogging and superior storage stability.
The infrared sensitive silver halide emulsion used in the invention refers to a silver halide emulsion exhibiting sensitivity to light having the wavelengths longer than the visible light wavelengths of 400 to 700 nm. The infrared sensitive silver halide light sensitive material used in the invention refers to a light sensitive material capable of forming a black-and-white image through developing, fixing and washing; a light sensitive material having an emulsion layer containing a coupler, a colored coupler or a DIR compound and capable of forming a color image through developing, bleach-fixing and washing; or a light sensitive material capable of forming an image upon thermal development without being subjected to wet processing, i.e., thermally developable photosensitive material.
The compounds represented by formula (1) to (6) will be described below.
The 5- or 6-membered condensed rings completed by an atomic group represented by Z1 include a condensed cyclohexene ring, a condensed benzene ring, a condensed thiophene ring, a condensed pyridine ring, and a condensed naphthalene ring. Exemplary examples thereof include a benzoxazole ring, tetrahydrobenzoxazole ring, naphthooxazole ring, benzonephthooxazole ring, benzothiazole ring, tetrahydrobenzothiazole ring, naphthothiazole ring, benzonaphthothiazole ring; thienothiazole ring, thianaphthenothiazole ring, pyridothiazole ring, benzoselenazole ring, tetrahydrobenzoselenazole ring, naphthoselenazole ring, benzonaphthoselenazole ring, quinoline ring, 3,3-dialkylindolenine and 3,3-dialkylpyridopyrroline. Any substituent such as one represented by W1 to W4 described later can be substituted on the ring described above.
Examples of the aliphatic group represented by R1, R11, R21, R22, R31, R32, R41, R42, R51 and R52 include a branched or straight-chained alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, butyl, pentyl, I-pentyl, 2-ethyl-hexyl, octyl, decyl), an alkenyl group having 3 to 10 carbon atoms (e.g., 2-propenyl, 3-butenyl, 1-methyl-3-propenyl, 3-pentenyl, 1-methyl-3-butenyl, 4-hexenyl), and an aralkyl group having 7 to 10 carbon atoms (e.g., benzyl, phenethyl). These groups may further be substituted with a substituent, including groups such as a lower alkyl group (e.g., methyl, ethyl, propyl), a halogen atom (e.g., fluorine atom, chlorine atom, or bromine atom), a vinyl group, an aryl group (e.g., phenyl, p-tolyl, p-bromophenyl), trifluoromethyl, an alkoxy group (e.g., methoxy, ethoxy, methoxyethoxy), an aryloxy group (e.g., phenoxy, p-tolyloxy), cyano, a sulfonyl group (e.g., methanesulfonyl, trifluoromethansulfonyl), p-toluenesulfonyl), an alkoxycarbonyl group (e.g., ethoxycarbonyl, butoxycarbonyl), an amino group (e.g., amino, biscarboxymethylamino), an aryl group (e.g., phenyl, carboxyphenyl), a heterocyclic group (e.g., tetrahydrofurfuryl, 2-pyrrolidinone-1-yl), an acyl group (e.g., acetyl, benzoyl), an ureido group (e.g., ureido, 3-methylureido, 3-phenylureido), a thioureido group (e.g., thioureido, 3-methylthioureido), an alkylthio group (e.g., methylthio, ethylthio), an arylthio group (e.g., phenylthio), a heterocyclic-thio group (e.g., 2-thienythio, 3-thienylthio, 2-imidazolylthio), a carbonyloxy group (e.g., acetyloxy, propanoyloxy, benzoyloxy), an acylamino group (e.g., acetylamino, benzoylamino); and hydrophilic groups, such as a sulfo group, a carboxy group, a phosphono group, a sulfate group, hydroxy, mercapto, sulfino group, a carbamoyl group (e.g., carbamoyl, n-methylcarbamoyl, N,N-tetramethylenecarbamoyl), a sulfamoyl group (e.g., sulfamoyl, N,N-3-oxapentamethylenaminosulfonyl), a sulfonamido group (e.g., methanesulfonamido, butanesulfoneamido), a sulfonylaminocarbonyl group(e.g., methanesulfonylaminocarbonyl, ethanesulfonylaminocarbonyl), an acylaminosulfonyl group (e.g., acetoamidosulfonyl, methoxyacetoamidosulfonyl), an acylaminocarbonyl group (e.g., acetoamidocarbonyl, methoxyacetoamidocarbonyl), and a sulfinylaminocarbonyl group (e.g., methasulfinylaminocarbonyl, ethanesulfinylaminocarbonyl). Examples of aliphatic groups substituted by a hydrophilic group include carboxymethyl, carboxypentyl, 3-sulfatobutyl, 3-sulfopropyl, 2-hydroxy-3-sulfopropyl, 4-sulfobutyl, 5-sulfopentyl, 3-sulfopentyl, 3-sulfinobutyl, 3-phosphonopropyl, hydroxyethyl, N-methanesulfonylcarbamoylmethyl, 2-carboxy-2-propenyl, o-sulfobenzyl, p-sulfobenzyl and p-carboxybenzyl.
The lower alkyl group represented by R include a straight-chained or branched one having 1 to 5 carbon atoms, such as methyl, ethyl, @propyl, pentyl and isopropyl. The cycloalkyl group includes, e.g., cyclopropyl, cyclobutyl and cyclopentyl. The aralkyl group includes, e.g., benzyl, phenethyl, p-methoxyphenylmethyl and o-acetylaminophenylethyl; the lower alkoxy group includes one having 1 to 4 carbon atoms, including methoxy, ethoxy, propoxy and i-propoxy; the aryl group includes substituted or unsubstituted one, such as phenyl, 2-naphthyl, 1-naphthyl, o-tolyl, o-methoxyphenyl, m-chlorophenyl, m-bromophenyl, p-tolyl and p-ethoxyphenyl. These groups may be substituted by a substituent group, such as a phenyl group, a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom), an alkoxy group or hydroxy.
The unsubstituted lower alkyl group represented by Ra or Rb includes those which are cited in R described above.
The lower alkyl group represented by Rc, Rd, Re or Rf includes a straight-chained or branched one having 1 to 5 carbon atoms, such as methyl, ethyl, @propyl, pentyl and isopropyl. The cycloalkyl group includes, e.g., cyclopropyl, cyclobutyl and cyclopentyl. The aralkyl group includes, e.g., benzyl, phenethyl, p-methoxyphenylmethyl and o-acetylaminophenyl-ethyl; the aryl group includes substituted or unsubstituted one, such as phenyl, 2-naphthyl, 1-naphthyl, o-tolyl, o-methoxyphenyl, m-chlorophenyl, m-bromophenyl, p-tolyl and p-ethoxyphenyl; and the heterocyclic group includes substituted or unsubstituted one, such as 2-furyl, 5-methyl-2-furyl, 2-thienyl, 2-imidazolyl, 2-methyl-1-imidazolyl, 4-phenyl-2-thiazolyl, 5-hydroxy-2-benzothiazolyl, 2-pyridyl and 1-pyrrolyl. These groups, as described above, may be substituted by a substituent group, such as a phenyl group, a halogen atom, an alkoxy group or hydroxy.
Examples of the substituents represented by W1 to W4, W11 to W14, W21 to W24, W31 to W34, W41 to W44 and W51 to W54 include an alkyl group (e.g., methyl, ethyl, butyl, I-butyl), an aryl group (including monocyclic and polycyclic ones such as phenyl and naphthyl), a heterocyclic group (e.g., thienyl, furyl, pyridyl, carbazolyl, pyrrolyl, indolyl), a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom), a vinyl group, trifluoromethyl, an alkoxy group (e.g., methoxy, ethoxy, methoxyethoxy), an aryloxy group (e.g., phenoxy, p-tolyloxy), a sulfonyl group (e.g., methanesulfonyl, p-toluenesulfonyl), an alkoxycarbonyl group (e.g., ethoxycarbonyl, butoxycarbonyl), an amino group (e.g., amino, biscarboxymethylamino), an acyl group (e.g., acetyl, benzoyl), an ureido group (e.g., ureido, 3-methylureido), a thioureido group (e.g., thioureido, 3-methylthioureido), an alkylthio group (e.g., methylthio, ethylthio), an alkenyl thio group, an arylthio group (e.g., phenylthio), hydroxy and styryl.
These groups may be substituted by the same substituents as described in the aliphatic group represented by R1. Examples of substituted alkyl group include 2-methoxyethyl, 2-hydroxyethyl, 3-ethoxycarbonylpropyl, 2-carbamoylethyl, 2-methanesulfonylethyl, 3-methanesulfonylaminopropyl, benzyl, phenethyl, carboxymethyl, carboxyethyl, allyl, and 2-furylethyl. Examples of substituted aryl groups include p-carboxyphenyl, p-N,N-dimethylaminophenyl, p-morpholinophenyl, p-methoxyphenyl, 3,4-dimethoxyphenyl, 3,4-methylenedioxyphenyl, 3-chlorophenyl, and p-nitrophenyl. Further, examples of substituted heterocyclic group include 5-chloro-2-pyridyl, 2-ethoxycarbonyl-2-pyridyl and 5-carbamoyl-2-pyridyl. W1 and W2, W3 and W4, W11 and W12, W13 and W14, W21 and W22, W23 and W24, W31 and W32, W33 and W34, W41 and W42, W43 and W44, W51 and W52 or W53 and W54 each pair may combine to form a condensed ring, such as 5- or 6-membered saturated or unsaturated condensed carbon rings, which are further substituted by substituents as described in the aliphatic group.
Among the groups represented by V1 to V9, V11 to V13, V21 to V29, and V31 to V33, the halogen atom includes, e.g., a fluorine atom, chlorine atom, bromine atom and iodine atom; the amino group includes, e.g., amino, dimethylamino, diphenylamino, and methylphenylamino; the alkylthio group includes substituted and substituted ones, such as phenylthio or m-fluorphenylthio; the lower alkyl group includes straight-chained or branched one having five or less carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl or isopropyl; the lower alkoxy group includes one having four or less carbon atoms, such as methoxy, ethoxy, propoxy, or isopropoxy; the aryl group includes substituted and unsubstituted ones, such as phenyl, 2-naphthyl, 1-naphthyl, o-tolyl, o-methoxyphenyl, m-chlorophenyl, m-bromophenyl, p-tolyl, and p-ethoxyphenyl; the aryloxy group includes substituted and unsubstituted ones, such as phenoxy, p-tolyloxy, and m-carboxyphenyloxy; and the heterocyclic group includes substituted or unsubstituted ones, such as 2-furyl, 5-methyl-2-furyl2-thienyl, 2-imidazolyl, 2-methyl-1-imidazolyl, 4-phenyl-2-thiazolyl, 5-hydroxy-2-benzothiazolyl, 2-pyridyl, and 1-pyrrolyl. These groups may further be substituted by a substituent group, such as a phenyl group, a halogen atom, alkoxy group, or hydroxy. V1 and V3, V2 and V4, V3 and V5, V4 and V6, V5 and V7, V6 and V8, V7 and V9, V11 and V13, V21 and V23, V22 and V24, V23 and V25, V24 and V26, V25 and V27, V26 and V28, V27 and V29, and V31 and V33 each pair may combine to form a 5- to 7-membered ring, such as a cyclopentene ring, cyclohexene ring, cycloheptene ring, and decalin ring, each of which may further be substituted by a lower alkyl group, lower alkoxy group or aryl group, as described in R.
The methylene group represented by L1 to L9, L11 to L15, L41 to L49 and L51 to L55 each are a substituted or unsubstituted methylene group. Examples of the substituent thereof include fluorine and chlorine atoms, a substituted or unsubstituted lower alkyl group(e.g., methyl, ethyl, I-propyl, benzyl), and a substituted or unsubstituted alkoxy group (e.g., methoxy, ethoxy), a substituted or unsubstituted aryloxy group (e.g., phenoxy, naphthoxy), a substituted or unsubstituted aryl group (e.g., phenyl, naphthyl, p-tolyl, o-carboxyphenyl), N(U1)(U2), xe2x80x94SRg, a substituted or unsubstituted heterocyclic group [e.g., 2-thienyl, 2-furyl, N,Nxe2x80x2-bis(methoxyethyl)barbituric acid], in which Rg is a lower alkyl group, an aryl group or a heterocyclic group and examples of xe2x80x94SRg include methylthio, ethylthio, benzylthio, phenylthio and tolylthio groups; U1 and U2 are each a substituted or unsubstituted lower alkyl group or aryl group, provided that V1 and V2 may combine to form a 5- or 6-membered nitrogen containing heterocyclic ring (e.g., pyrazole ring, pyrrole ring, pyrrolidine ring, morpholine ring, pyperizine ring, pyridine, pyrimidine ring, etc.). Methylene groups which are adjacent or distant by one may combine to form a 5- or 6-membered ring.
In cases where the compound represented by formulas (1) to (6) is substituted with a cationic- or anionic-charged group, a counter ion is formed by an anionic or cationic equivalent to compensate an intramolecular charge. As an ion necessary to compensate the intramolecular charge, which is represented by X1, X11, X21, X31, X41 or X51, examples of cations include a proton, an organic ammonium ion (e.g., triethylammonium, triethanolammonium) and inorganic cations (e.g., cations of lithium, sodium and potassium); and examples of acid anions include halide ions (e.g., chloride ion, bromide ion, iodide ion), p-toluenesulfonate ion, perchlorate ion, tetrafluoroborate ion, sulfate ion, methylsulfate ion, ethylsulfate ion, methanesulfonate ion, trifluoromethanesulfonate ion).
The infrared sensitizing dye according to the invention is characterized in that a three ring-condensed heterocyclic nucleus is formed by bonding between a nitrogen atom contained in a benzothiazole ring and a carbon atom at a peri-position; and that the dye is a long chain polymethine dye, in which a sulfonyl group is substituted on the benzene ring of the benzothiazole ring. It is not definitely clarified why the use of these dyes leads to high sensitivity, low fogging and superior storage stability. It is assumed that the dye containing a three ring-condensed heterocyclic ring easily form an aggregate of a stacking structure when forming a dye structure. It is further assumed that a benzoazole ring substituted with a sulfinyl or sulfonyl group contains a sulfur atom exhibiting higher hydrophilicity and less interaction with silver than a thioether, and an electron-withdrawing action of this group lowers the ground state of the dye to advantageously prevent direct influences such as fogging, leading to advantageous effects such as antifogging or stabilization. Furthermore, the polarized structure between an oxygen atom and a sulfur atom may advantageously act on interaction between dye molecules, stabilizing the dye aggregate.
Of spectral sensitizing dyes represented by formulas (3) to (5) and (6), those which have a substituted methine chain are preferred; and those which have a structure of forming a ring on the methine chain are also preferred.
Exemplary examples of the sensitizing dyes represented by formulas (1) to (4) and the sensitizing dyes represented by by formulas (5) and (6) are shown below, but are not limited to these.
Compound represented by Formulas (1) to (4): 
Compound represented by Formulas (5) and (6): 
The infrared sensitizing dyes and spectral sensitizing dyes described above can be readily synthesized according to the methods described in F. M. Hammer, The Chemistry of Heterocyclic Compounds vol.18, xe2x80x9cThe cyanine Dyes and Related Compoundsxe2x80x9d (A. Weissberger ed. Interscience Corp., New York, 1964); J. Ber., 64, 1664-1674 (1931); Ukrain. Khim. Zhur., 21, 744-749 (1955); British patents 625,245 and 895,930; U.S. Pat. Nos. 2,320,439 and 2,398,999.
Synthesis of the compounds described above are exemplarily explained as below.
In 2.5 ml of m-cresol was dissolved 4.51 g (0.02 molw) of 5,6-dihydro-2-methyl-4H-thoazolo[5,4,3-ij]quinolinium hydrochloric acid salt, which was synthesized according to the method described in Ukrain. Khim. Zhur., 21, 744-749 (1955) and 2.0 g (0.01 mole) of 2,7-dimethoxy-1,4,5,8-tetrahydronaphthalene was added thereto and heated in an oil bath at 120xc2x0 C. for 10 min., while stirring. Subsequently, 50 ml ethanol and 1 g triethylamine was further added thereto and heated in a water bath at 70xc2x0 C. for 30 min., while stirring. To the reaction mixture was added 1 g of sodium tetrafluoroborate and cooled with stirring to form precipitates. The resulting crystals were separated from the solution by filtration and were recrystallized from a mixed solvent of fluoroalcohol and methanol to obtain 0.41 g purified product. Mass spectrum gave a molecular ion peak at 507, which was in agreement with a molecular weight of the intended structure. The absorption maximum in methanol was 744.4 nm (xcex5: 221,000).
3-ethyl-2-methyl-5-methylthiobenzothiazolium-p-tolyenesulfonate of 19.75 g (0.05 mole) and 2,7-dimethoxy-1,4,5,8-tetrahydronaphthalene of 28.8 g (0.15 mole) were mixed in 40 ml dimethylsulfoxide and heated in a oil bath at 120xc2x0 C. for 15 min, while stirring. The reaction mixture was added with ethyl acetate, diluted to five times and crystallized out of solution upon sufficiently cooling. The crystals was separated from the solution by filtration and washed with ethyl acetate to obtain 16.2 g of substituted product. The produced intermediate exhibited an absorption maximum at 496 nm in methanol(xcex5: 57,700).
Dye Condensation
5,6-Dihydroxy-2-methyl-4H-thiazolo[5,4,3-ij]quinolinium hydrochloric acid salt of 10.4 g, p-toluenesulfonic acid ethyl ester of 2.26 g (0.01 mole) and 3-ethyl-2-[(7methyl-3,4,5,6-tetrahydro-1H-2-naphthylidene)methyl]-5-methylthiobenzothiazolium-p-toluenesulfonate of 5.56 g (0.01 mole) were dissolved in 5.0 ml m-cresol and heated in an oil bath at 120xc2x0 C. for 15 min., while stirring. Subsequently, 100 ml ethanol and 2 g triethylamine were added thereto and heated in a water bath at 80xc2x0 C. for 30 min., while stirring. The reaction mixture was added with 2 g of sodium tetrafluoroborate and crystallized out of solution upon cooling with stirring. The crystals were separated from the solution by filtration, washed with water and recrystallized from mixed solvents of fluoroalcohol and methanol to obtain 1.1 g purified product. Mass spectrum gave a molecular ion peak at 541, which was in agreement with a molecular weight of the intended structure. The absorption maximum in methanol was 749.50 nm (xcex5: 193,000).
In 100 ml methanol was dissolved 3.9 g (0.02 mole) of 2-methyl-5-methylthiobenzothiazole and 100 ml aqueous solution containing 5.2 g (0.024 mole) sodium periodate was added thereto and stirred at room temperature for 1 hr. The reaction mixture was condensed under reduced pressure to remove methanol, an aqueous 5% sodium hydrogen carbonate solution was added to make weak alkaline, was further added with sodium chloride and extracted with ethyl acetate. The extracted solution was condensed and the resulting precipitates were separated from solution by filtration. Crystals were purified by recrystallization from mixed solvents of ethyl acetate and n-hexane (at a yield of 75%), exhibiting a melting point of 95.97xc2x0 C.
2-Methyl-5-methylsulfinylbenzothiazole of 2.1 g (0.01 mole) and ethyl p-toluenesulfonate of 2.4 g (0.012 mole) were mixed and heated in an oil bath at 120 to 130xc2x0 C. for 8 hrs. The reaction mixture was separated by means of column chromatography using silica gel and mixed solvents of ethyl acetate/methanol (2:1) and eluted with methanol solution. To the methanol eluate was added activated carbon, stirred and separated by filtration. The resulting filtrate was condensed under reduced pressure and dried to obtain 1.7 g of intended viscous solid substance. This intermediate compound was used in the following dye condensation reaction without purification.
Dye Condensation
3-ethyl-2-methyl-5-methylsulfinylbenzothiazolium-p-toluenesulfonate of 1.6 g (0.004 mole) and 2,7-dimethoxy-1,4,5,8-tetrahydronaphthalene of 0.3 g (0.0015 mole) were dissolved in 0.5 m-cresol and heated in an oil bath at 120xc2x0 C. for 15 min., while stirring. Subsequently, 5 ml ethanol and 0.g triethylamine were added thereto and heated in a water bath at 80xc2x0 C. for 10 min., while stirring. The reaction mixture was added with 4 ml of aqueous 50% ethanol solution containing 0.4 g of sodium tetrafluoroborate and crystallized out of solution upon cooling with stirring. The crystals were separated from the solution by filtration, washed with water and recrystallized from mixed solvents of fluoroalcohol and methanol to obtain 0.15 g purified product. Mass spectrum gave a molecular ion peak at 607, which was in agreement with a molecular weight of the intended structure. The absorption maximum in methanol was 747.30 nm (xcex5: 228,000).
The sensitizing dye used in the invention may be used alone or in combination. Specifically, a combination of dyes represented by formula (3) and (5), and a combination of dyes represented by formulas (4) and (6) are preferred. In either case when used alone or used in combination, the total amount of the dye(s) to be incorporated is preferably 1xc3x9710xe2x88x926 to 5xc3x9710xe2x88x923, more preferably 1xc3x9710xe2x88x925 to 2.5xc3x9710xe2x88x923, and still more preferably 4xc3x9710xe2x88x925 to 1xc3x9710xe2x88x923 mol per mol of silver halide.
In cases when dyes are used in combination, the dyes can be incorporated in any proportion. The dye may be directly dispersed in a silver halide emulsion. Alternatively, the may be dissolved in an appropriate solvent such as methanol, ethanol, n-propanol, methyl cellosolve, acetone, water, pyridine, or a mixture thereof and added to the emulsion in the form of a solution. Ultrasonic can also be employed. The sensitizing dye can be added in such a manner that a dye is dissolved in a volatile organic solvent, the resulting solution is dispersed in a hydrophilic colloidal medium and the dispersion is added to the emulsion, as described in U.S. Pat. No. 3,469,987; a water-insoluble dye is dispersed in aqueous medium without being dissolved and the dispersion is added to the emulsion, as described in JP-B 46-24185 (hereinafter, the term, JP-B means a published Japanese Patent); a dye is dissolved using a surfactant and the resulting solution is added to the emulsion, as described in U.S. Pat. No. 3,822,135; a dye is dissolved using a compound capable of shifting to longer wavelengths and the solution is added to the emulsion, as described in JP-A 51-74624; or a dye is dissolved in an acid substantially containing no water and the solution is added to the emulsion, as described in JP-A 50-80826. Further, the dye may be added according to the method described in U.S. Pat. Nos. 2,912,343, 3,342,605, 2,996,287 and 3,492,835. The dye may be homogeneously dispersed in a silver halide emulsion before coating on a support, or may be dispersed at any stage of preparing the silver halide emulsion.
In cases when used in combination, the dyes can be independently or in the form of a mixture dispersed in a silver halide emulsion. Together with the dye(s), a visible region-absorbing dye capable of exhibiting supersensitization, a dye not exhibiting supersensitization, or a compound having no absorption in the visible region may be incorporated into the emulsion. Usable sensitizing dyes and substances exhibiting supersensitization in combination with the dye are described in Research Disclosure (hereinafter, also denoted as xe2x80x9cRDxe2x80x9d) vol. 176, item 17643 (December, 1978) page 23, section IV-J; JP-B 49-15500 and 43-4933; and JP-A 59-9032, 3-15049 and 62-123454.
Techniques described in Research Disclosure No. 308119 (hereinafter, also denoted such as RD 308119) are applicable to the silver halide emulsions used in the invention, as shown below. The silver halide emulsions include those which are used in color and black-and-white photographic light sensitive materials.
The silver halide emulsion according to the invention is subjected to physical ripening, chemical ripening and spectral sensitization. As additives used in these processes are shown compounds described in Research Disclosure No. 17643, No. 18716 and No. 308119 (hereinafter, denoted as RD 17643, RD 18716 and RD 308119), as below.
Photographic additives usable in the invention are also described, as below.
A variety of couplers can be employed in the invention and examples thereof are described in research Disclosures described above. Relevant description portions are shown below.
Additives used in the invention can be added by dispersing methods described in RD 308119 XIV. In the invention are employed supports described in RD 17643, page 28; RD 18716, page 647-648; and RD 308119 XIX. In the photographic material according to the invention, there can be provided auxiliary layers such as a filter layer and interlayer, as described in RD 308119 VII-K, and arranged a variety of layer orders such as normal layer order, reverse layer order and unit layer arrangement.
Silver halide photographic light sensitive materials used in the invention can be processed by use of commonly known developing agents described in T. H. James, The Theory of the Photographic Process, Fourth edition, page 291 to 334; and Journal of American Chemical Society, 73, 3100 (1951), including, e.g., hydroquinone, p-aminophenol, N-methyl-p-aminophenol, 2,4-aminophenol, 2,4-diaminophenol as described in JP-A 4-15641; 1-phenyl-3-pyrazolidones such as 1-phenyl-3-pyrazolidone, 1-phenyl-4-methyl4-hydroxymethyl-3-pyrazolidone, and 5,5-dimethyl-1-phenyl-3-pyrazolidone and according the conventional method described in RD17643, pages 28-29, RD18716, page 615 and RD308119, XIX.
Infrared sensitizing dyes used in the invention can also be advantageously applicable to thermally developable photosensitive materials. As is conducted in the techniques of conventional silver halide emulsions, after the dye is allowed to adsorb onto silver halide grains, the silver halide grain emulsion may be mixed with an organic silver salt. Alternatively, after an organic silver salt and silver halide are mixed, the dye may be added thereto in a manner similar to the conventional silver halide emulsions described above. Plural dyes may be used to perform supersensitization. For example, the infrared sensitizing dye may be used in combination with sensitizing dyes described in RD17643 section IV-X (December 1978, page 23) and Rd18431, section X (August 1979, page 437), or other sensitizing dyes. Further, a supersensitizer exhibiting no absorption in the visible region may be used in combination, as used in conventional silver halide techniques. As described later, instead of preparing silver halide in ex citu and mixing it with the dye, spectral sensitization can be achieved by converting a part of the organic silver salt to silver halide and by further adding the dye thereto.
The present invention also relates to thermally developable photosensitive materials containing an infrared sensitizing dye represented by formulas (1) to (4), a preparation method thereof and an image recording method and image forming method by use thereof.
These infrared sensitizing dyes are superior in adsorption to silver halide and enhancing sensitivity and storage stability, as compared to conventionally used infrared sensitizing dyes. However, there still remains problems such that in cases when applied to thermally developable photosensitive materials, marked reduction in sensitivity after pre-exposure storage of the photosensitive material or being allowed to stand in the form a solution at the stage of preparing a coating solution; and improvements thereof are desired. It is contemplated that such problems are caused due to the fact that the thermally developable photosensitive material is difference in constitution from the conventional silver halide photographic material, which is to be subjected to liquid processing. The present invention was accomplished as a result of the inventor""s study to solve the problems.
Thermally developable photosensitive materials comprise a photosensitive silver halide, an organic silver salt, a reducing agent, adjuvants such as a tone modifier (also called image tone-providing agent or activator toner) and a binder. Specifically, the tone modifier also promotes development and compounds having a strong affinity for a silver ion are employed. Examples of representative tone modifiers include phthalazines, phthalazinones, and benzene-polycarboxlic acids and their anhydrides. The tone modifier concerns oxidation-reduction reaction of the organic silver salt and reducing agent, having a function of enhancing silver image density or blackening image tone. The tone modifier may be incorporated into a non-photosensitive layer or a photosensitive silver halide layer. In any case thereof, it was found that adding the tone modifier immediately before coating a photosensitive coating solution was preferred, enhancing sensitivity and reducing variation in photographic performance during standing of the photosensitive coating solution. It is contemplated that these advantageous effects are related to infrared sensitizing dyes used in the invention. Such effects are also unexpected and surprising.
The reason for the effects is not definitely clarified. It is contemplated that these compounds have a high affinity for a silver compound, affecting adsorption of a sensitizing dye, and a protic compound of the tone modifier undergoes protonation to a sensitizing dye, possibly affecting absorption and stability of the sensitizing dye. In fact, there was found a difference in sensitivity spectrum (or spectral sensitivity distribution) between a photosensitive material which was coated after standing a coating solution added with a toner modifier and a photosensitive material which was coated immediately after adding the toner modifier.
Phthalazines and phthalazinones may be substituted and preferred substituents include substituted alkyl, substituted aryl, hydroxy, halogen, substituted amino, substituted amido, substituted ester, substituted nitro and substituted alkoxy. Exemplary examples thereof include phthalazine, phthalazinone, 4-(1-naphthyl)phthalazine, 4-(1-naphthyl)phthalazinone, 6-chlorophthalazine, 60chlorophthalazinone, 5,7-dimethyloxyphthalazine, 5,7-dimethyloxuphthalazinone, 4-phthalazine and 4-phthalazinone. Benzenepolycarboxylic acids may be substituted and preferred substituents include substituted alkyl, substituted aryl, hydroxy, halogen, substituted amino, substituted amido, substituted ester, substituted nitro and substituted alkoxy. Preferred benzenepolycarboxylic acids are substituted or unsubstituted benzenedicarboxylic acids, substituted or unsubstituted benzenetricarboxylic acids, including phthalic acids, terephthalic acids, isophthalic acids and trimellitic acids. Substituted or unsubstituted benzenedicarboxylic acids are specifically preferred and phthalic acids are most preferred.
Phthalic acids may be substituted and preferred substituents include substituted alkyl, substituted aryl, hydroxy, halogen, substituted amino, substituted amido, substituted ester, substituted nitro and substituted alkoxy. The benzenepolycarboxylic acids may be in the form of an anhydride, such as phthalic acid and its anhydride, 4-methylphthalic acid and its anhydride, 4-nitrophthalic acid and its anhydride, and tetrachlorophthalic acid and its anhydride.
In the photosensitive material according to the invention, at least one of these compounds is incorporated into a photosensitive silver halide layer or a non-photosensitive layer. The non-photosensitive layer refers to a layer containing no photosensitive silver halide and provided on the same side as the layer containing photosensitive silver halide, including a protective layer.
In cases when added into the non-photosensitive layer, the tone modifier may be at any time between after the start of preparation of the photosensitive layer coating solution and immediately before coating. In cases when added into the photosensitive layer, it is preferred to add the tone modifier into a coating solution of the photosensitive layer immediately before coating. In this case, the expression xe2x80x9cimmediately beforexe2x80x9d means 2 hrs to 1 sec., and 1 hr. to 10 sec. before the start of coating. In cases when incorporated into the photosensitive layer, the phthalazine, phthalazinones, or benzenepolycarboxylic acids, the amount thereof is preferably 0.1 to 20% by weight, and more preferably 0.2 to 15% by weight, based on total silver including organic silver salts and silver halide. In cases when incorporated into another layer such as non-photosensitive protective layer, the same or more amount to be incorporated is preferred. In cases when incorporated into a protective layer, 1.1 to 3 times the amount to be incorporated into the photosensitive layer is preferred. A large excess of the tone modifier causes bleeding on thermal development to stain a heated drum, causing stains in the photosensitive material. In cases when the tone modifier is incorporated into an infrared sensitizing dye-containing layer or another layer, photosensitive materials with high sensitivity and superior storage stability can be obtained by adding the tone modifier and promptly making completion of coating and drying within a period of time after adding it.
The compounds described above are most effective as a tone modifier. Further, compounds described below are also effective as a tone modifier. Thus, other preferred tone modifiers usable in the invention are disclosed in Research Disclosure 176, item 17029. Exemplary examples thereof include:
imides (for example, phthalimide), cyclic imides, pyrazoline-5-one, and quinazolinone (for example, succinimide, 3-phenyl-2-pyrazoline-5-on, 1-phenylurazole, quinazoline and 2,4-thiazolidione); naphthalimides (for example, N-hydroxy-1,8-naphthalimide); cobalt complexes (for example, cobalt hexaminetrifluoroacetate), mercaptans (for example, 3-mercapto-1,2,4-triazole); N-(aminomethyl)aryldicarboxyimides (for example, N-(dimethylaminomethyl)phthalimide); blocked pyrazoles, isothiuronium derivatives and combinations of certain types of light-bleaching agents (for example, combination of N,Nxe2x80x2-hexamethylene(1-carbamoyl-3,5-dimethylpyrazole), 1,8-(3,6-dioxaoctane)bis-(isothiuroniumtrifluoroacetate), and 2-(tribromomethyl-sulfonyl)benzothiazole; merocyanine dyes (for example, 3-ethyl-5-((3-etyl-2-benzothiazolinylidene-(benzothiazolinylidene))-1-methylethylidene-2-thio-2,4-oxazolidinedione); phthalazinone, phthalazinone derivatives or metal salts thereof (for example, 4-(1-naphthyl)phthalazinone, 6-chlorophthalazinone, 5,7-dimethylphthalazinone, and 2,3-dihydro-1,4-phthalazinedione); combinations of phthalazinone and sulfinic acid derivatives (for example, 6-chlorophthalazinone and benzenesulfinic acid sodium, or 8-methylphthalazinone and p-trisulfonic acid sodium); combinations of phthalazine and phthalic acid; combinations of phthalazine (including phthalazine addition products) with at least one compound selected from maleic acid anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylenic acid derivatives and anhydrides thereof (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, and tetrachlorophthalic acid anhydride); quinazolinediones, benzoxazine, naphthoxazine derivatives, benzoxazine-2,4-diones (for example, 1,3-benzoxazine-2,4-dione); pyrimidines and asymmetry-triazines (for example, 2,4-dihydroxypyrimidine), and tetraazapentalene derivatives (for example, 3,6-dimercapto-1,4-diphenyl-1H,4H-2,3a,5,6a-tatraazapentalene). Preferred image color control agents include phthalazone or phthalazine.
It is preferred to apply a heteroatom-containing macrocyclic compound to the thermally developable photosensitive materials used in the invention. The heteroatom containing macrocyclic compound refers to a nine- or more membered macrocyclic compound containing at least a heteroatom selected from a nitrogen atom, an oxygen atom, a sulfur atom and a selenium atom. The macrocyclic compound is preferably a 12- to 18-membered ring. Representative compounds thereof include compounds commonly known as a crown ether, which was synthesized by Pederson in 1967 and a number of which have been synthesized since its specific report. The compounds are detailed in C. J. Pederson, Journal of American Chemical Society vol. 86 (2495), 7017-7036 (1967); G. W. Gokel and S. H. Korzeniowski, xe2x80x9cMacrocyclic Polyether Synthesisxe2x80x9d, Springer-Vergal (1982); xe2x80x9cChemistry of Crown Etherxe2x80x9d edited by Oda, Shono and Tabuse, published by Kyoritsu Shuppan (1978); xe2x80x9cHost-Guestxe2x80x9d edited by Tabuse, published by Kyoritsu Shuppan (1979); and Suzuki and Koga, Yuki Gosei Kagaku (Journal of Organic Synthetic Chemistry) vol. 45 (6) 571-582 (1987).
Exemplary examples of the heteroatom containing macrocyclic compounds used in the invention are shown below, but are not limited to these examples. 
The heteroatom containing macrocyclic compound may be added at any stage after forming silver halide and until preparing a coating solution, and is added preferably prior to adding the sensitizing dye. The heteroatom containing macrocyclic compounds are generally incorporated into the thermally developable photosensitive layer through solution in organic solvents such as methanol, ethanol or fluorinated alcohols, or water. In cases where solubility is not sufficient, dissolution-promoting agent may be used in combination, including potassium acetate, potassium iodide, potassium fluoride, potassium p-toluenesulfonate, KBF4, KPF6, NH4BF4 and NH4PF6. Any compound containing an ion capable of forming an inclusion compound together with the heteroatom containing macrocyclic compound, which is able to improve solubility may be usable as the dissolution-promoting agent.
Thermally developable photosensitive materials are disclosed, for example, in U.S. Pat. Nos. 3,152,904 and 3,457,075, and D. Morgan, xe2x80x9cDry Silver Photographic Materialxe2x80x9d and D. Morgan and B. Shely, xe2x80x9cThermally Processed Silver Systemsxe2x80x9d (Imaging Processes and Materials) Neblette, 8th Edition, edited by Sturge, V. Walworth, and A. Shepp, page 2, 1969), etc. of these, the thermally developable photosensitive material used in the invention is characterized in that they are thermally developed at temperature of 80 to 140xc2x0 C. so as to obtain images without fixation.
Silver halide grains of photosensitive silver halide in the present invention work as a light sensor. In order to minimize cloudiness after image formation and to obtain excellent image quality, the less the average grain size, the more preferred, and the average grain size is preferably less than 0.1 xcexcm, more preferably between 0.01 and 0.1 xcexcm, and still more preferably between 0.02 and 0.08 xcexcm. The average grain size as described herein is defined as an average edge length of silver halide grains, in cases where they are so-called regular crystals in the form of cube or octahedron. Furthermore, in cases where grains are not regular crystals, for example, spherical, cylindrical, and tabular grains, the grain size refers to the diameter of a sphere having the same volume as the silver grain. Furthermore, silver halide grains are preferably monodisperse grains. The monodisperse grains as described herein refer to grains having a monodispersibility obtained by the formula described below of less than 40%; more preferably less than 30%, and most preferably from 0.1 to 20%.
Monodispersibility=(standard deviation of grain diameter)/(average grain diameter)xc3x97100(%)
The silver halide grain shape is not specifically limited, but a high ratio accounted for by a Miller index [100] plane is preferred. This ratio is preferably at least 50%; is more preferably at least 70%, and is most preferably at least 80%. The ratio accounted for by the Miller index [100] face can be obtained based on T. Tani, J. Imaging Sci., 29, 165 (1985) in which adsorption dependency of a [111] face or a [100] face is utilized.
Furthermore, another preferred silver halide shape is a tabular grain. The tabular grain as described herein is a grain having an aspect ratio represented by r/h of at least 3, wherein r represents a grain diameter in xcexcm defined as the square root of the projection area, and h represents thickness in xcexcm in the vertical direction. Of these, the aspect ratio is preferably between 3 and 50. The grain diameter is preferably not more than 0.1 xcexcm, and is more preferably between 0.01 and 0.08 xcexcm. These are described in U.S. Pat. Nos. 5,264,337, 5,314,789, 5,320,958, and others. In the present invention, when these tabular grains are used, image sharpness is further improved. The composition of silver halide may be any of silver chloride, silver chlorobromide, silver iodochlorobromide, silver bromide, silver iodobromide, or silver iodide.
Silver halide emulsions used in the invention can be prepared according to the methods described in P. Glafkides, Chimie Physique Photographique (published by Paul Montel Corp., 19679; G. F. Duffin, Photographic Emulsion Chemistry (published by Focal Press, 1966); V. L. Zelikman et al., Making and Coating of Photographic Emulsion (published by Focal Press, 1964). Any one of acidic precipitation, neutral precipitation and ammoniacal precipitation is applicable and the reaction mode of aqueous soluble silver salt and halide salt includes single jet addition, double jet addition and a combination thereof. Silver halide may be incorporated into the image forming layer by any means so that the silver halide is arranged so as to be close to reducible silver source. Silver halide may be mixed with a previously-prepared organic silver salt. Alternatively, silver halide may be added into a solution used for preparing an organic silver salt so that silver halide is arranged closely to the organic silver salt prepared.
Photosensitive silver halide emulsions usable in the thermally developable photosensitive materials according to the invention can be prepared according to the methods commonly known in the photographic art, such as single jet or double jet addition, or ammoniacal, neutral or acidic precipitation. Thus, the silver halide emulsion is prepared in advance and then the emulsion is mixed with other components of the invention to be incorporated into the composition used in the invention. To sufficiently bring the photosensitive silver halide into contact with an organic silver salt, there can be applied such techniques that polymers other than gelatin, such as polyvinyl acetal are employed as a protective colloid in the formation of photosensitive silver halide, as described in U.S. Pat. Nos. 3,706,564, 3,706,565, 3,713,833 and 3,748,143, British Patent 1,362,970; gelatin contained in a photosensitive silver halide emulsion is degraded with an enzyme, as described in British Patent 1,354,186; or photosensitive silver halide grains are prepared in the presence of a surfactant to save the use of a protective polymer, as described in U.S. Pat. No. 4,076,539.
It is preferred to prepare silver halide in advance and mix it with an organic silver salt. Alternatively, silver halide may be formed by reaction of an organic silver salt and a halide ion to convert a part of the organic silver salt to silver halide. A combination of these may be applicable. The content of silver halide is preferably 0.75 to 30% by weight, based on an organic silver salt.
Silver halide preferably occludes ions of metals belonging to Groups 6 to 11 of the Periodic Table. Preferred as the metals are W; Fe, Co, Ni, Cu, Ru, Rh, Pd, Re, Os, Ir, Pt and Au. These metals may be introduced into silver halide in the form of a complex. In the present invention, regarding the transition metal complexes, six-coordinate complexes represented by the general formula described below are preferred:
Formula: (ML6)m:
wherein M represents a transition metal selected from elements in Groups 6 to 11 of the Periodic Table; L represents a coordinating ligand; and m represents 0, 1-, 2-, 3- or 4-. Exemplary examples of the ligand represented by L include halides (fluoride, chloride, bromide, and iodide), cyanide, cyanato, thiocyanato, selenocyanato, tellurocyanato, azido and aquo, nitrosyl, thionitrosyl, etc., of which aquo, nitrosyl and thionitrosyl are preferred. When the aquo ligand is present, one or two ligands are preferably coordinated. L may be the same or different. Particularly preferred examples of M include rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir) and osmium (Os).
Exemplary examples of transition metal ligand complexes are shown below.
1: [RhCl6]3xe2x88x92
2: [RuCl6]3xe2x88x92
3: [ReCl6]3xe2x88x92
4: [RuBr6]3xe2x88x92
5: [OsCl6]3xe2x88x92
6: [IrCl6]2xe2x88x92
7: [Ru(NO)Cl5]2xe2x88x92
8: [RuBr4(H2O)]2xe2x88x92
9: [Ru(NO) (H2O)Cl4]xe2x88x92
10: [RhCl5(H2O)]2xe2x88x92
11: [Re(NO)Cl5]2xe2x88x92
12: [Re(NO)(CN)5]2xe2x88x92
13: [Re(NO)Cl(CN)4]2xe2x88x92
14: [Rh(NO)2Cl4]xe2x88x92
15: [Rh(NO)(H2O)Cl4]xe2x88x92
16: [Ru(NO)(CN)5]2xe2x88x92
17: [Fe(CN)6]3xe2x88x92
18: [Rh(NS)Cl5]2xe2x88x92
19: [Os(NO)Cl5]2xe2x88x92
20: [Cr(NO)Cl5]2xe2x88x92
21: [Re(NO)Cl5]xe2x88x92
22: [Os(NS)Cl4(TeCN)]2xe2x88x92
23: [Ru(NS)Cl5]2xe2x88x92
24: [Re(NS)Cl4(SeCN)]2xe2x88x92
25: [Os(NS)Cl(SCN)4]2xe2x88x92
26: [Ir(NO)Cl5]2xe2x88x92
27: [Ir(NS)Cl5]2xe2x88x92
One type of these metal ions or complex ions may be employed and the same type of metals or the different type of metals may be employed in combinations of two or more types. Generally, the content of these metal ions or complex ions is suitably between 1xc3x9710xe2x88x929 and 1xc3x9710xe2x88x922 mole per mole of silver halide, and is preferably between 1xc3x9710xe2x88x928 and 1xc3x9710xe2x88x924 mole. Compounds, which provide these metal ions or complex ions, are preferably incorporated into silver halide grains through addition during the silver halide grain formation. These may be added during any preparation stage of the silver halide grains, that is, before or after nuclei formation, growth, physical ripening, and chemical ripening. However, these are preferably added at the stage of nuclei formation, growth, and physical ripening; furthermore, are preferably added at the stage of nuclei formation and growth; and are most preferably added at the stage of nuclei formation. These compounds may be added several times by dividing the added amount. Uniform content in the interior of a silver halide grain can be carried out. As disclosed in JP-A No. 63-29603, 2-306236, 3-167545, 4-76534, 6-110146, 5-273683, the metal can be non-uniformly occluded in the interior of the grain.
These metal compounds can be dissolved in water or a suitable organic solvent (for example, alcohols, ethers, glycols, ketones, esters, amides, etc.) and then added. Furthermore, there are methods in which, for example, an aqueous metal compound powder solution or an aqueous solution in which a metal compound is dissolved along with NaCl and KCl is added to a water-soluble silver salt solution during grain formation or to a water-soluble halide solution; when a silver salt solution and a halide solution are simultaneously added, a metal compound is added as a third solution to form silver halide grains, while simultaneously mixing three solutions; during grain formation, an aqueous solution comprising the necessary amount of a metal compound is placed in a reaction vessel; or during silver halide preparation, dissolution is carried out by the addition of other silver halide grains previously doped with metal ions or complex ions. Specifically, the preferred method is one in which an aqueous metal compound powder solution or an aqueous solution in which a metal compound is dissolved along with NaCl and KCl is added to a water-soluble halide solution. When the addition is carried out onto grain surfaces, an aqueous solution comprising the necessary amount of a metal compound can be placed in a reaction vessel immediately after grain formation, or during physical ripening or at the completion thereof or during chemical ripening.
Silver halide grain emulsions used in the invention may be desalted after the grain formation, using the methods known in the art, such as the noodle washing method and flocculation process.
The photosensitive silver halide grains used in the invention is preferably subjected to a chemical sensitization. As preferable chemical sensitizations, well known chemical sensitizations in this art such as a sulfur sensitization, a selenium sensitization and a tellurium sensitization are usable. Furthermore, a noble metal sensitization using gold, platinum, palladium and iridium compounds and a reduction sensitization are available. As the compounds preferably used in the sulfur sensitization, the selenium sensitization and the tellurium sensitization, well known compounds can be used and the compounds described in JP-A 7-128768 is usable. Examples of the compounds used in the noble metal sensitization include chloroauric acid, potassium chloroaurate, potassium aurothiocyanate, gold sulfide, gold selenide, compounds described U.S. Pat. No. 2,448,060 and British Patent No. 618,061. Examples of the compounds used in the reduction sensitization include ascorbic acid, thiourea dioxide, stannous chloride, aminoiminomethane-sulfinic acid, hydrazine derivatives, borane compounds, silane compounds and polyamine compounds. The reduction sensitization can be carried out by ripening an emulsion with keeping the pH and pAg at not less than 7 and not more than 8.3, respectively. Furthermore, the reduction sensitization can be carried out by introducing a silver ion alone at a time during the grain formation.
Halide composition of silver halide used in the invention is not specifically limited, including silver chloride, silver chlorobromide, silver iodochlorobromide, silver bromide, silver iodobromide, and silver iodide. Of these, silver iodobromide is preferred to improve adsorption property. Silver halide grains used in the thermally developable photosensitive material are preferably those which have an average iodide content in the vicinity of the grain surface of 0.1 to 10 mol %, and more preferably 1 to 7 mol %. In the thermally developable photosensitive materials, higher iodide silver halide is preferred in terms of adsorption of a sensitizing dye, as compared to conventional silver halide photographic materials. The average iodide content in the vicinity of the grain surface refers to an average iodide content to a depth of 5 nm from the surface, which can be determined by the XPS method (i.e., X-ray Photoelectron Spectroscopy), according to the following procedure. A sample is cooled to a temperature of not higher than xe2x88x92110xc2x0 C. under ultra-high vacuum of not more than 1xc3x9710xe2x88x928 torr, exposed to MgKxcex1-line as X-ray for probe at a X-ray source voltage of 15 kV and X-ray source current of 40 mA and measured with respect to Ag3d5/2, Br3d and I3d3/2 electrons. The thus measured integrated peak intensity is corrected with a sensitivity factor and from the obtained intensity ratio can be determined halide composition in the vicinity of the grain surface. Cooling the sample reduces measurement errors, which are due to destruction of the sample occurred when exposed at room temperature, enhancing measurement precision. Cooling to a temperature of xe2x88x92110xc2x0 C. prevents destruction of the sample at an acceptable level in the measurement.
The amount of silver halide used in the thermally developable photosensitive material is preferably not more than 50%, more preferably 0.1 to 25%, and still more preferably 0.1 to 15%, based on the total amount of silver halide and organic silver salt.
Photosensitive silver halide used in the thermally developable photosensitive material of the invention can be formed simultaneously with the formation of organic silver salt by allowing a halide component such as a halide ion to concurrently be present together with organic silver salt-forming components and further introducing a silver ion thereinto during the course of preparing the organic silver salt.
Alternatively, a silver halide-forming component is allowed to act onto a pre-formed organic silver salt solution or dispersion or a sheet material containing an organic silver salt to convert a part of the organic silver salt to photosensitive silver halide. The thus formed silver halide is effectively in contact with the organic silver salt, exhibiting favorable actions. In this case, the silver halide forming component refers to a compound capable of forming silver salt upon reaction with the organic silver salts. Such a compound can be distinguished by the following simple test. Thus, a compound to be tested is to be mixed with the organic silver salt, and if necessary, the presence of a peal specific to silver halide can be confirmed by the X-ray diffractometry, after heating. Compounds that have been confirmed to be effective as a silver halide-forming component include inorganic halide compounds, onium halides, halogenated hydrocarbons, N-halogene compounds and other halogen containing compounds. These compounds are detailed in U.S. Pat. No. 4,009,039, 3,457,075 and 4,003,749, British Patent 1,498,956 and JP A 53-27027 and 53-25420. Exemplary examples thereof are shown below:
(1) Inorganic halide compound: e.g., a halide compound represented by formula, MXn, in which M represents H, NH4 or a metal atom; n is 1 when M is H or NH4 and a number equivalent to a valence number of the metal atom when M is the metal atom; the metal atom includes lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium, zinc, cadmium, mercury, tin, antimony, chromium, manganese, cobalt, rhodium, and cerium, and molecular halogen such as aqueous bromine being also effective;
(2) Onium halide: e.g., quaternary ammonium halides such as trimethylphenylammonium bromide, cetylethyldimethylammonium bromide, and trimethylbenzylammonium bromide; and tertiary sulfonium halides such as trimethylsulfonium iodide;
(3) Halogenated hydrocarbons: e.g., iodoform, bromoform, carbon tetrachloride and 2-brom-2-methylpropane;
(4) N-halogeno compounds: e.g., N-chlorosuccinimide, N-bromosucciimde, N-bromophthalimide, N-bromoacetoamide, N-iodosuccinimide, N-bromophthalazinone, N-bromooxazolinone, N-chlorophthalazinone, N-bromoacetoanilide, N,N-dibromobenzenesulfonamide, N-bromo-N-methylbenzenesulfonamide, 1,3-dibromo-4,4-dimethylhydantoin and N-bromourazole;
(5) Other halogen containing compounds: e.g., triphenylmethyl chloride, triphenylmethyl bromide 2-bromoacetic acid, 2-bromoethanol and dichlorobenzophenone.
The silver halide forming component is used stoichiometrically in a small amount per organic silver salt. Thus, it is preferably 0.001 to 0.7 mol, and more preferably 0.03 to 0.5 mol per mol of organic silver salt. The silver halide-forming component may be used in combination. Conditions including a reaction temperature, reaction time and reaction pressure during the process of converting a part of the organic silver salt to silver halide using the silver halide forming component can be appropriately set in accordance with the purpose of preparation. The reaction temperature is preferably xe2x88x9220xc2x0 C. to 70xc2x0 C., the reaction time is preferably 0.1 sec to 72 hrs. and the reaction pressure is preferably atmospheric pressure. The reaction is performed preferably in the presence of polymer as a binder, wherein the polymer to be used is preferably 0.01 to 100 weight parts, and more preferably 0.1 to 10 weight parts per 1 weight part of an organic silver salt.
The thus formed photosensitive silver halide can be chemically sensitized with a sulfur containing compound, gold compound, platinum compound, palladium compound, silver compound, tin compound, chromium compound or their combination. The method and procedure for chemical sensitization are described in U.S. Pat. No. 4,036,650, British Patent 1,518,850, JP-A 51-22430, 51-78319 and 51-81124. As described in U.S. Pat. No. 3,980,482, a low molecular weight amide compound may be concurrently present to enhance sensitivity at the time of converting a part of the organic silver salt to photosensitive silver halide.
To improve reciprocity law failure or adjust contrast, the photosensitive silver halide may be contained with metal ions of the 6th group to 10th group in the periodical table, such as Rh, Ru, Re, Ir, Os, Fe and their complexes and complex ions. Specifically, complex ions are preferred, e.g., Ir complex ions such as IrCl62xe2x88x92 are preferably contained to improve reciprocity law failure.
Organic silver salts used in the invention are reducible silver source, and silver salts of organic acids or organic heteroacids are preferred and silver salts of long chain fatty acid (preferably having 10 to 30 carbon atom and more preferably 15 to 25 carbon atoms) or nitrogen containing heterocyclic compounds are more preferred. Specifically, organic or inorganic complexes, ligand of which have a total stability constant to a silver ion of 4.0 to 10.0 are preferred. Exemplary preferred complex salts are described in RD17029 and RD29963, including organic acid salts (for example, salts of gallic acid, oxalic acid, behenic acid, stearic acid, palmitic acid, lauric acid, etc.); carboxyalkylthiourea salts (for example, 1-(3-carboxypropyl)thiourea, 1-(3-caroxypropyl)-3,3-dimethylthiourea, etc.); silver complexes of polymer reaction products of aldehyde with hydroxy-substituted aromatic carboxylic acid (for example, aldehydes (formaldehyde, acetaldehyde, butylaldehyde, etc.), hydroxy-substituted acids (for example, salicylic acid, benzoic acid, 3,5-dihydroxybenzoic acid, 5,5-thiodisalicylic acid, silver salts or complexes of thiones (for example, 3-(2-carboxyethyl)-4-hydroxymethyl-4-(thiazoline-2-thione and 3-carboxymethyl-4-thiazoline-2-thione), complexes of silver with nitrogen acid selected from imidazole, pyrazole, urazole, 1.2,4-thiazole, and 1H-tetrazole, 3-amino-5-benzylthio-1,2,4-triazole and benztriazole or salts thereof; silver salts of saccharin, 5-chlorosalicylaldoxime, etc.; and silver salts of mercaptides. Of these organic silver salts, silver salts of fatty acids are preferred, and silver salts of behenic acid, arachidinic acid and stearic acid are specifically preferred.
The organic silver salt compound can be obtained by mixing an aqueous-soluble silver compound with a compound capable of forming a complex. Normal precipitation, reverse precipitation, double jet precipitation and controlled double jet precipitation described in JP-A 9-127643 are preferably employed. For example, to an organic acid is added an alkali metal hydroxide (e.g., sodium hydroxide, potassium hydroxide, etc.) to form an alkali metal salt soap of the organic acid (e.g., sodium behenate, sodium arachidinate, etc.), thereafter, the soap and silver nitrate are mixed by the controlled double jet method to form organic silver salt crystals. In this case, silver halide grains may be concurrently present.
In the present invention, organic silver salts have an average grain diameter of 2 xcexcm or less and are monodispersed. The average diameter of the organic silver salt as described herein is, when the grain of the organic salt is, for example, a spherical, cylindrical, or tabular grain, a diameter of the sphere having the same volume as each of these grains. The average grain diameter is preferably between 0.05 and 1.5 xcexcm, and more preferably between 0.05 and 1.0 xcexcm. Furthermore, the monodisperse as described herein is the same as silver halide grains and preferred monodispersibility is between 1 and 30%.
It is also preferred that at least 60% of the total of the organic silver salt is accounted for by tabular grains. The tabular grains refer to grains having a ratio of an average grain diameter to grain thickness, i.e., aspect ratio (denoted as AR) of 3 or more:
AR=average diameter (xcexcm)/thickness (xcexcm)
To obtain such tabular organic silver salts, organic silver salt crystals are pulverized together with a binder or surfactant, using a ball mill. Thus, using these tabular grains, photosensitive materials exhibiting high density and superior image fastness are obtained.
To prevent hazing of the photosensitive material, the total amount of silver halide and organic silver salt is preferably 0.5 to 2.2 g in equivalent converted to silver per m2, leading to high contrast images. The amount of silver halide is preferably 50% by weight or less, more preferably 25% by weight or less, and still more preferably 0.1 to 15% by weight, based on the total silver amount.
Reducing agents are preferably incorporated into the thermally developable photosensitive material of the present invention. Examples of suitable reducing agents are described in U.S. Pat. Nos. 3,770,448, 3,773,512, and 3,593,863, and Research Disclosure Items 17029 and 29963, and include the following: aminohydroxycycloalkenone compounds (for example, 2-hydroxypiperidino-2-cyclohexane); esters of amino reductones as the precursor of reducing agents (for example, piperidinohexose reducton monoacetate); N-hydroxyurea derivatives (for example, N-p-methylphenyl-N-hydroxyurea); hydrazones of aldehydes or ketones (for example, anthracenealdehyde phenylhydrazone; phosphamidophenols; phosphamidoanilines; polyhydroxybenzenes (for example, hydroquinone, t-butylhydroquinone, isopropylhydroquinone, and (2,5-dihydroxy-phenyl)methylsulfone); sulfydroxamic acids (for example, benzenesulfhydroxamic acid); sulfonamidoanilines (for example, 4-(N-methanesulfonamide)aniline); 2-tetrazolylthiohydroquinones (for example, 2-methyl-5-(1-phenyl-5-tetrazolylthio)hydroquinone); tetrahydroquionoxalines (for example, 1,2,3,4-tetrahydroquinoxaline); amidoxines; azines (for example, combinations of aliphatic carboxylic acid arylhydrazides with ascorbic acid); combinations of polyhydroxybenzenes and hydroxylamines, reductones and/or hydrazine; hydroxamic acids; combinations of azines with sulfonamidophenols; xcex1-cyanophenylacetic acid derivatives; combinations of bis-xcex2-naphthol with 1,3-dihydroxybenzene derivatives; 5-pyrazolones, sulfonamidophenol reducing agents, 2-phenylindane-1,3-dione, etc.; chroman; 1,4-dihydropyridines (for example, 2,6-dimethoxy-3,5-dicarboethoxy-1,4-dihydropyridine); bisphenols (for example, bis(2-hydroxy-3-t-butyl-5-methylphenyl)methane, bis(6-hydroxy-m-tri)mesitol, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,5-ethylidene-bis(2-t-butyl-6-methyl)phenol, UV-sensitive ascorbic acid derivatives and 3-pyrazolidones. Of these, particularly preferred reducing agents are hindered phenols.
As hindered phenols, listed are compounds represented by the general formula (A) described below: 
wherein R represents a hydrogen atom or an alkyl group having from 1 to 10 carbon atoms (for example, xe2x80x94C4H9, 2,4,4-trimethylpentyl), and Rxe2x80x2 and Rxe2x80x3 each represents an alkyl group having from 1 to 5 carbon atoms (for example, methyl, ethyl, t-butyl).
Exemplary examples of the compounds represented by the formula (A) are shown below. 
The used amount of reducing agents represented by the above-mentioned general formula (A) is preferably between 1xc3x9710xe2x88x922 and 10 moles, and is more preferably between 1xc3x9710xe2x88x922 and 1.5 moles per mole of silver.
Binders suitable for the thermally developable photosensitive material to which the present invention is applied are transparent or translucent, and generally colorless. Binders are natural polymers, synthetic resins, and polymers and copolymers, other film forming media; for example, gelatin, gum arabic, poly(vinyl alcohol), hydroxyethyl cellulose, cellulose acetate, cellulose acetatebutylate, poly(vinyl pyrrolidone), casein, starch, poly(acrylic acid), poly(methyl methacrylic acid), poly(vinyl chloride), poly(methacrylic acid), copoly(styrene-maleic acid anhydride), copoly(styrene-acrylonitrile, copoly(styrene-butadiene, poly(vinyl acetal) series [e.g., poly(vinyl formal) and poly(vinyl butyral), polyester series, polyurethane series, phenoxy resins, poly(vinylidene chloride), polyepoxide series, polycarbonate series, poly(vinyl acetate) series, cellulose esters, poly(amide) series. Of these binders are preferred aqueous-insoluble polymers such as cellulose acetate, cellulose acetate-butylate and poly(vinyl butyral); and poly(vinyl formal) and poly(vinyl butyral) are specifically preferred as a polymer used in the thermally developable photosensitive layer; and cellulose acetate and cellulose acetate-butylate are preferably used in a protective layer and backing layer.
A non-photosensitive layer may be provided on the photosensitive layer to protect the surface or prevent abrasion marks. Binder used in the non-photosensitive layer may be the same as or different from the binder used in the photosensitive layer.
The amount of the binder in a photosensitive layer is preferably between 1.5 and 6 g/m2, and is more preferably between 1.7 and 5 g/m2. The binder content of less than 1.5 g/m2 tends to increase a density of unexposed area to levels unacceptable to practical use.
In the present invention, a matting agent is preferably incorporated into the image forming layer side. In order to minimize the image abrasion after thermal development, the matting agent is provided on the surface of a photosensitive material and the matting agent is preferably incorporated in an amount of 0.5 to 30 percent in weight ratio with respect to the total binder in the emulsion layer side.
In cases where a non photosensitive layer is provided on the opposite side of the support to the photosensitive layer, it is preferred to incorporate a matting agent into at least one of the non-photosensitive layer (and more preferably, into the surface layer) in an amount of 0.5 to 40% by weight, based on the total binder on the opposite side to the photosensitive layer.
Materials of the matting agents employed in the present invention may be either organic substances or inorganic substances. Examples of the inorganic substances include silica described in Swiss Patent No. 330,158, etc.; glass powder described in French Patent No. 1,296,995, etc.; and carbonates of alkali earth metals or cadmium, zinc, etc. described in U.K. Patent No. 1.173,181, etc. Examples of the organic substances include starch described in U.S. Pat. No. 2,322,037, etc.; starch derivatives described in Belgian Patent No. 625,451, U.K. Patent No. 981,198, etc.; polyvinyl alcohols described in Japanese Patent Publication No. 44-3643, etc.; polystyrenes or polymethacrylates described in Swiss Patent No. 330,158, etc.; polyacrylonitriles described in U.S. Pat. No. 3,079,257, etc.; and polycarbonates described in U.S. Pat. No. 3,022,169.
The shape of the matting agent may be crystalline or amorphous. However, a crystalline and spherical shape is preferably employed. The size of a matting agent is expressed in the diameter of a sphere having the same volume as the matting agent. The particle diameter of the matting agent in the present invention is referred to the diameter of a spherical converted volume. The matting agent employed in the present invention preferably has an average particle diameter of 0.5 to 10 xcexcm, and more preferably of 1.0 to 8.0 xcexcm. Furthermore, the variation coefficient of the size distribution is preferably not more than 50 percent, is more preferably not more than 40 percent, and is most preferably not more than 30 percent. The variation coefficient of the size distribution as described herein is a value represented by the formula described below:
(Standard deviation of particle diameter)/(average particle diameter)xc3x97100
The matting agent according to the present invention can be incorporated into any layer. In order to accomplish the object of the present invention, the matting agent is preferably incorporated into the layer other than the photosensitive layer layer, and is more preferably incorporated into the farthest layer from the support.
Addition methods of the matting agent include those in which a matting agent is previously dispersed into a coating composition and is then coated, and prior to the completion of drying, a matting agent is sprayed. When plural matting agents are added, both methods may be employed in combination.
The thermally developable photosensitive material according to the invention comprises a support having thereon at least one photosensitive layer, and the photosensitive layer may only be formed on the support. The photosensitive layer may be composed of a plurality of layers. To adjust gradation, layers may be arranged in such a manner as a high-speed layer/low-speed layer or a low-speed layer/high-speed layer. Further, at least one non-photosensitive layer is preferably formed on the photosensitive layer. In order to control the amount or wavelength distribution of light transmitted through the photosensitive layer, a filter layer may be provided on the same side as the photosensitive layer, and/or an antihalation layer, that is, a backing layer on the opposite side. Dyes or pigments may also be incorporated into the photosensitive layer. As the usable dyes, those which can absorb aimed wavelength in desired wavelength region can be used, preferred are compounds described in JP-A Nos. 59-6481, 59-182436, U.S. Pat. No. 4,594,312, European Patent Publication Nos. 533,008, 652,473, JP-A Nos. 2-216140, 4-348339, 7-191432, 7-301890. Furthermore, these non-photosensitive layers may contain the above-mentioned binder, a matting agent and a lubricant such as a polysiloxane compound, a wax and liquid paraffin.
Suitable tone modifiers usable in the invention a) include those used in the invention b). Tone mdifiers are preferably incorporated into the thermally developable photosensitive material used in the present invention. Examples of preferred tone modifiers, which are disclosed in Research Disclosure Item 17029, include the following:
imides (for example, phthalimide), cyclic imides, pyrazoline-5-one, and quinazolinone (for example, succinimide, 3-phenyl-2-pyrazoline-5-on, 1-phenylurazole, quinazoline and 2,4-thiazolidione); naphthalimides (for example, N-hydroxy-1,8-naphthalimide); cobalt complexes (for example, cobalt hexaminetrifluoroacetate), mercaptans (for example, 3-mercapto-1,2,4-triazole); N-(aminomethyl)aryldicarboxyimides (for example, N-(dimethylaminomethyl)phthalimide); blocked pyrazoles, isothiuronium derivatives and combinations of certain types of light-bleaching agents (for example, combination of N,Nxe2x80x2-hexamethylene(1-carbamoyl-3,5-dimethylpyrazole), 1,8-(3,6-dioxaoctane)bis-(isothiuroniumtrifluoroacetate), and 2-(tribromomethyl-sulfonyl)benzothiazole; merocyanine dyes (for example, 3-ethyl-5-((3-etyl-2-benzothiazolinylidene-(benzothiazolinylidene))-1-methylethylidene-2-thio-2,4-oxazolidinedione); phthalazinone, phthalazinone derivatives or metal salts thereof (for example, 4-(1-naphthyl)phthalazinone, 6-chlorophthalazinone, 5,7-dimethylphthalazinone, and 2,3-dihydro-1,4-phthalazinedione); combinations of phthalazinone and sulfinic acid derivatives (for example, 6-chlorophthalazinone and benzenesulfinic acid sodium, or 8-methylphthalazinone and p-trisulfonic acid sodium); combinations of phthalazine and phthalic acid; combinations of phthalazine (including phthalazine addition products) with at least one compound selected from maleic acid anhydride, and phthalic acid, 2,3-naphthalenedicarboxylic acid or o-phenylenic acid derivatives and anhydrides thereof (for example, phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid, and tetrachlorophthalic acid anhydride); quinazolinediones, benzoxazine, naphthoxazine derivatives, benzoxazine-2,4-diones (for example, 1,3-benzoxazine-2,4-dione); pyrimidines and asymmetry-triazines (for example, 2,4-dihydroxypyrimidine), and tetraazapentalene derivatives (for example, 3,6-dimercapto-1,4-diphenyl-1H,4H-2,3a,5,6a-tatraazapentalene). Preferred tone modifiers include phthalazone or phthalazine.
In the present invention, to restrain or accelerate development for the purpose of controlling the development, to enhance the spectral sensitive efficiency, or to enhance the reservation stability before and after the development, a mercapto compound, a disulfide compound and a thione compound can be incorporated in the photosensitive material. In cases where the mercapto compound is used in the present invention, any compound having a mercapto group can be used, but preferred compounds are represented by the following formulas, Arxe2x80x94SM and Arxe2x80x94Sxe2x80x94Sxe2x80x94Ar, wherein M represents a hydrogen atom or an alkaline metal atom, Ar represents an aromatic ring compound or a condensed aromatic ring compound having at least a nitrogen, sulfur, oxygen, selenium or tellurium. Preferable aromatic heterocyclic ring compounds include benzimidazole, naphthoimidazole, benzothiazole, naphthothiazole, benzoxazole, naphthooxazole, benzoselenazole, benzotellurazole, imidazole, oxazole, pyrazole, triazole, thiadiazole, tetrazole, triazine, pyrimidine, pyridazine, pyrazine, pyridine, purine, quinoline or quinazoline. These aromatic heterocyclic ring compounds may contain a substituent selected from a halogen atom (e.g., Br and Cl), a hydroxy group, an amino group, a carboxy group, an alkyl group (e.g., alkyl group having at least a carbon atom, preferably 1 to 4 carbon atoms) and an alkoxy group (e.g., alkoxy group having at least a carbon atom, preferably 1 to 4 carbon atoms). Examples of mercapto-substituted aromatic heterocyclic ring compounds include 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercapto-5-methylbenzothiazole, 3-mercapto-1,2,4-triazole, 2-mercaptoquinoline, 8-mercaptopurine, 2,3,5,6-tetrachloro-4-pyridinethiol, 4-hydroxy-2-mercaptopyrimidine and 2-mercapto-4-phenyloxazole, but the exemplified compounds according to the present invention are not limited thereto.
Antifoggants may be incorporated into the thermally developable photosensitive material to which the present invention is applied. The substance which is known as the most effective antifoggant is a mercury ion. The incorporation of mercury compounds as the antifoggant into photosensitive materials is disclosed, for example, in U.S. Pat. No. 3,589,903. However, mercury compounds are not environmentally preferred. As mercury-free antifoggants, preferred are those antifoggants as disclosed in U.S. Pat. Nos. 4,546,075 and 4,452,885, and JP-A 59-57234. Particularly preferred mercury-free antifoggants are heterocyclic compounds having at least one substituent, represented by C(X1) (X2) (X3) (wherein X1 and X2 each represent halogen, and X3 represents hydrogen or halogen), as disclosed in U.S. Pat. Nos. 3,874,946 and 4,756,999. As examples of suitable antifoggants, employed preferably are compounds described in paragraph numbers [0030] through [0036] of JP-A 9-288328. Further, as another examples of suitable antifoggants, employed preferably are compounds described in paragraph numbers [0062] and [0063] of JP-A 9-90550. Furthermore, other suitable antifoggants are disclosed in U.S. Pat. No. 5,028,523, and European Patent 600,587; 605,981 and 631,176.
In the thermally processable photosensitive material of the present invention, employed can be sensitizing dyes described, for example, in JP-A Nos. 63-159841, 60-140335, 63-231437, 63-259651, 63-304242, and 63-15245; U.S. Pat. Nos. 4,639,414, 4,740,455, 4,741,966, 4,751,175, and 4,835,096. Useful sensitizing dyes employed in the present invention are described, for example, in publications described in or cited in Research Disclosure Items 17643, Section IV-A (page 23, December 1978). Particularly, selected can advantageously be sensitizing dyes having the spectral sensitivity suitable for spectral characteristics of light sources of various types of scanners. For example, compounds described in JP-A Nos. 9-34078, 9-54409 and 9-80679 are preferably employed.
Various kinds of additives can be incorporated into a photosensitive layer, a non-photosensitive layer or other construction layers. Except for the compounds mentioned above, surface active agents, antioxidants, stabilizers, plasticizers, UV (ultra violet rays) absorbers, covering aids, etc. may be employed in the thermally developable photosensitive material according to the present invention. These additives along with the above-mentioned additives are described in Research Disclosure Item 17029 (on page 9 to 15, June, 1978) and can be employed.
Supports employed in the present invention are preferably, in order to minimize the deformation of images after development processing, plastic films (for example, polyethylene terephthalate, polycarbonate, polyimide, nylon, cellulose triacetate, polyethylene naphthalate). The thickness of the support is between about 50 and about 300 xcexcm, and is preferably between 70 and 180 xcexcm. Furthermore, thermally processed plastic supports may be employed. As acceptable plastics, those described above are listed. The thermal processing of the support, as described herein, is that after film casting and prior to the photosensitive layer coating, these supports are heated to a temperature at least 30xc2x0 C. higher than the glass transition point, preferably by not less than 35xc2x0 C. and more preferably by at least 40xc2x0 C. However, when the supports are heated at a temperature higher than the melting point, no advantages of the present invention are obtained. Commonly known casting methods and subbing methods are applicable to the support used in the invention, as described in JP-A 9-50094, items [0030]-[0070].
To improve an electrification property, a conducting compound such as a metal oxide and/or a conducting polymer can be incorporated into a construction layer. These compounds can be incorporated into any layer, preferably into a sublayer, a backing layer and an intermediate layer between a photosensitive layer and a sublayer, etc. In the present invention, the conducting compounds described in U.S. Pat. No. 5,244,773, column 14 through 20, are preferably used.
In cases where the thermally developable photosensitive material is specifically employed for the output of a printing image setter with an oscillation wavelength of 600 to 800 nm, hydrazine derivatives are preferably incorporated into the photosensitive material. Exemplary preferred hydrazine compounds are described in RD23515 (November, 1983, page 346), U.S. Pat. Nos. 4,080,207, 4,269,929, 4,276,364, 4,278,748, 4,385,108, 4,459,347, 4,478,928, 4,560,638, 4,686,167, 4,912,016, 4,988,604, 4,994,365, 5,041,355, and 5,104,769; British Patent 2,011,391B; European Patents 217,310, 301,799 and 356,898; JP-A 60-179734, 61-170733, 61-270744, 62-178246, 62-270948, 63-29751, 63-32538, 63-104047, 63-121838, 63-129337, 63-22374, 63-234244, 63-234245, 63-234246, 63-294552, 63-306438, 64-10233, 1-90439, 1-100530, 1-105041, 1-105943, 1-276128, 1-280747, 1-283548, 1-283549, 1-285940, 2-2541, 2-7057, 2-13958, 2-196234, 2-196235, 2-198440, 2-198441, 2-198442, 2-220042, 2-221953, 2-221954, 2-285342, 2-285343, 2-289843, 2-302750, 2-304550, 3-37642, 3-54549, 3-125134, 3-184039, 3-240036, 3-240037, 3-259240, 3-280038, 3-282536, 4-51143, 4-56842, 4-84134, 2-230233, 4-96053, 4-216544, 5-45761, 5-45762, 5-45763, 5-45764, 5-45765, 6-289524, and 9-160164.
Furthermore, other than those, employed can be compounds described in (Ka 1) of Japanese Patent Publication (hereinafter, denoted as JP-B) No. 6-77138, specifically, compounds described on pages 3 and 4 of the Publication; compounds represented by general formula (I) in JP-B No. 6-93082, specifically, compounds 1 through 38 described on pages 8 to 18 of the Publication; compounds represented by general formula (4), general formula (5), and general formula (6) in JP-A No. 6-230497, specifically, compounds 4-1 through 4-10 on pages 25 and 26, compounds 5-1 through 5-42 on pages 28 to 36, and compounds 6-1 through 6-7 on pages 39 and 40 of the Publication; compounds represented by general formula (I) and general formula (2) in JP-A No. 6-289520, specifically, compounds 1-1) through 1-17) and 2-1) on pages 5 to 7 of the Publication; compounds described in (Ka 2) and (Ka 3) of JP-A No. 6-313936, specifically, compounds described on pages 6 to 19 of the Publication; compounds described in (Ka 1) of JP-A No. 6-313951, specifically, compounds described on pages 3 to 5 of the Publication; compounds represented by general formula (I) in JP-A No. 7-5610, specifically, compounds I-1 through I-38 described on pages 5 to 10 of the Publication; compounds represented by general formula (II) in JP-A No. 7-77783, specifically, compounds II-1 through II-102 described on pages 10 to 27 of the Publication; and compounds represented by general formula (H) and general formula (Ha) in JP-A No. 7-104426, specifically, compounds H-1 through H-44 described on pages 8 to 15 of the Publication.
In addition to these materials, a variety of adjuvants may be incorporated into the photosensitive layer, non-photosensitive layer or other layer(s). Exemplarily, a surfactant, an antioxidant, a stabilizer, a plasticizer, a UV absorbent or a coating aid may be incorporated. As these adjuvants and other additives can be used compounds described in RD17029 (June, 1978, page 9-15).
Supports usable in the thermally developable photosensitive materials include various kinds of polymeric materials, glass, wool fabric, cotton fabric, paper, metal (e.g., aluminum) and those which are convertible to flexible sheets or rolls are preferred in terms of handling as information recording material. Preferred supports usable in thermally developable photosensitive materials are plastic resin films (e.g., cellulose acetate film, polyester film, polyethylene terephthalate film, polyethylene naphthalate film, polyamide film, polyimide film, cellulose triacetate film, polycarbonate film) and biaxially stretched polyethylene terephthalate film is specifically preferred. The thickness of the support is preferably 50 to 300 xcexcm, and more preferably 70 to 180 xcexcm.
In the present invention, to improve an electrification property, a conducting compound such as a metal oxide and/or a conducting polymer can be incorporated into a construction layer. These compounds can be incorporated into any layer, preferably into a sublayer, a backing layer and an intermediate layer between a photosensitive layer and a sublayer, etc. In the present invention, the conducting compounds described in U.S. Pat. No. 5,244,773, column 14 through 20, are preferably used.
The thermally developable photosensitive material according to the invention comprises a support having thereon a photosensitive layer, and preferably further on the photosensitive layer having a non-photosensitive layer. For example, it is preferred that a protective layer is provided on the photosensitive layer to protect the photosensitive layer and that a back coating layer is provided on the opposite side of the support to the photosensitive layer to prevent adhesion between photosensitive materials or sticking of the photosensitive material to a roller. Further, there may be provided a filter layer on the same side or opposite side to the photosensitive layer to control the amount or wavelengths of light transmitting the thermally developable photosensitive layer. Alternatively, a dye or pigment may be incorporated into the photosensitive layer. In this case, dyes described in JP-A 8-201959 are preferably used therein. The photosensitive layer may be comprised of plural layers. To adjust contrast, a high speed layer and low speed layer may be provided in combination. Various adjuvants may be incorporated into the photosensitive layer, non-photosensitive layer or other component layer(s).
The coating method of the photosensitive layer, protective layer and backing layer is not specifically limited. Coating can be conducted by any method known in the art, including air knife, dip-coating, bar coating, curtain coating, and hopper coating. Two or more layers can be simultaneously coated. As a solvent for coating solution are employed organic solvents such as methyl ethyl ketone (also denoted as MEK), ethyl acetate and toluene.
The thermally developable photosensitive material, which is stable at ordinary temperatures, is exposed and heated at a high temperature (preferably 80 to 200xc2x0 C., and more preferably 100 to 150xc2x0 C.) to undergo development. In cases when heated at a temperature of lower than 80xc2x0 C., sufficient image density can be obtained within a short time. Further, in cases when heated at a temperature of higher than 200xc2x0 C., a binder melts and is transferred to a roller, adversely affecting not only images but also transportability and a developing machine. The organic silver salt (functioning as an oxidant) and the reducing agent undergo oxidation-reduction reaction upon heating to form silver images. The reaction process proceeds without supplying any processing solution such as water.
Any light source within the infrared region is applicable to exposure of the thermally developable photosensitive material and infrared semiconductor lasers (780 nm, 820 nm) are preferred in terms of high power and transmission capability through the photosensitive material.
In the invention, exposure is preferably conducted by laser scanning exposure. It is also preferred to use a laser exposure apparatus, in which scanning laser light is not exposed at an angle substantially vertical to the exposed surface of the photosensitive material. The expression xe2x80x9claser light is not exposed at an angle substantially vertical to the exposed surfacexe2x80x9d means that laser light is exposed preferably at an angle of 55 to 88xc2x0, more preferably 60 to 86xc2x0, still more preferably 65 to 84, and optimally 70 to 82xc2x0. When the photosensitive material is scanned with laser light, the beam spot diameter on the surface of the photosensitive material is preferably not more than 200 xcexcm, and more preferably not more than 100 xcexcm. Thus, the less spot diameter preferably reduces an angle displacing from verticality of the laser incident angle. The lower limit of the beam spot diameter is 10 xcexcm. The thus laser scanning exposure can reduce deterioration in image quality due to reflection light, such as occurrence of interference fringe-like unevenness.
Exposure applicable in the invention is conducted preferably using a laser scanning exposure apparatus producing longitudinally multiple scanning laser light, whereby deterioration in image quality such as occurrence of interference fringe-like unevenness is reduced, as compared to scanning laser light with longitudinally single mode. Longitudinal multiplication can be achieved by a technique of employing backing light with composing waves or a technique of high frequency overlapping. The expression xe2x80x9clongitudinally multiplexe2x80x9d means that the exposure wavelength is not a single wavelength. The exposure wavelength distribution is usually not less than 5 nm and not more than 10 nm. The upper limit of the exposure wavelength distribution is not specifically limited but usually about 60 nm.
It is preferred that when subjected to thermal development, the thermally developable photosensitive material contains an organic solvent. Examples of solvents include ketones such as acetone, isophorone, ethyl amyl ketone, methyl ethyl ketone, methyl isobutyl ketone; alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, diacetone alcohol, cyclohexanol, and benzyl alcohol; glycols such as ethylene glycol, dimethylene glycol, triethylene glycol, propylene glycol and hexylene glycol; ether alcohols such as ethylene glycol monomethyl ether, and dimethylene glycol monomethyl ether; ethers such as ethyl ether, dioxane, and isopropyl ether; esters such as ethyl acetate, butyl acetate, amyl acetate, and isopropyl acetate; hydrocarbons such as n-pentane, n-hexane, n-heptane, cyclohexene, benzene, toluene, xylene; chlorinated compounds-such as chloromethyl, chloromethylene, chloroform, and dichlorobenzene; amines such as monomethylamine, dimethylamine, triethanol amine, ethylenediamine, and triethylamine; and water, formaldehyde, dimethylformaldehyde, nitromethane, pyridine, toluidine, tetrahydrofuran and acetic acid. The solvents are not to be construed as limiting these examples. These solvents may be used alone or in combination.
The solvent content in the photosensitive material can be adjusted by varying conditions such as temperature conditions at the drying stage after the coating stage. The solvent content can be determined by means of gas chromatography under the conditions suitable for detecting the solvent. The total solvent content (based on weight) of the thermally developable photosensitive material used in the invention is preferably adjusted to be 40 to 4500 ppm, and more preferably 100 to 4000 ppm (based on the weight of constituting components of the photosensitive material, except for a support). The solvent content within the range described above leads to a thermally developable photosensitive material with low fog density as well as high sensitivity.
The use of novel infrared sensitizing dyes relating to the invention is not limited to silver halide light sensitive photographic materials and thermally developable photosensitive materials each of which contains silver halide as a photosensitive material or photosensor. These novel infrared sensitizing dyes are applicable to any photosensitive composition, in which these dye are capable of functioning as a photoreceptor, including a photosensitive composition containing a non-silver photosensitive substance which is capable of being spectral-sensitized with this novel infrared sensitizing dye and a photosensitive composition containing the infrared sensitizing dye, light absorption of which enable to form images. Exemplary examples of the photosensitive composition include a quinoneazide containing photosensitive material used for lithographic printing plate and a photosensitive composition used for free radical photography. Photosensitive materials to make a lithographic printing plate, for example, are described in U.S. Pat. Nos. 5,430,699, and 3,799,778; JP-A 53-13342, 60-37549 and 9-171254.